McCarthy got in between that defensive duo for both his goals, but United's problems stemmed from the Portuguese champions' relentless probing of the visitors' left flank, where Fortune was protected by Ryan Giggs.

Making light of their defensive frailities, United got off to the perfect start with their first real attack providing the opening to the goal.

After Jorge Costa fouled Giggs just outside the Porto box, the United winger rolled the ball to Scholes, whose powerful, rising free-kick was spilled by Baia allowing Fortune to strike the rebound home.

The Brazilian Carlos Alberto almost immediately equalised for Porto, but his curling shot went just over.

KEY MOMENTS

14 mins: Fortune gives Man Utd the lead

29 mins: McCarthy equalises for Porto as United concede their first goal in five Champions League games

78 mins: McCarthy gives Porto the lead

87 mins: Keane is sent off for the 11th time in his career

Dmitri Alenichev should have equalised after turning inside Brown and Phil Neville only to then delay his shot allowing Gary Neville time to get in a crucial block.